Can someone please explain to me...

[superhauntedvagina]

The difference between first formula and follow on formula.

I see countless posts where people are advised to not use follow on formula as it's the same as first formula / is a marketing tool / the HV said I didn't need to change.

In my experience, follow on formula is usually cheaper so if it's exactly the same as first formula, why couldn't you use follow on from birth?

Follow on is not as regulated as first milk and has higher iron content. You can't advertise first milk so follow on was invented to get round these rules as you can advertise follow on milk.
I did switch as it was cheaper so it is an option. You just can't use it before 6 months as its not tailored enough for newborn babies

DD was EBF until about 9 months, and now has the very occasional bottle of follow on milk.

As PP said the main difference is that there's more iron. It's mostly a marketing point, but also cheeper.

I think the message is that if your baby is happy on newborn milk you don't need to worry about changing, but if you're ok to change or if you start with formula after 6 months it's totally fine to use.